Rocket Height

1. The problem statement, all variables and given/known data
A rocket, initially at rest on the ground, accelerates straight upward from rest with constant acceleration 53.9 m/s^2. The acceleration period lasts for time 7.00 s until the fuel is exhausted. After that, the rocket is in free fall.

Find the maximum height ymax reached by the rocket. Ignore air resistance and assume a constant acceleration due to gravity equal to 9.80 m/s^2 .

3. The attempt at a solution
I got 2,641m, but it says that the rocket will still be moving upwards after the fuel is lost. How would I find how far the rocket goes after it runs out of fuel?

From the moment the fuel finishes, only one force acts upon the rocket: gravity.
So find the the velocity the rocket possesses after those 7 seconds of propulsion and then use the constant acceleration formulae to find the height at which the rocket has v=0.